Elustondo 2014 Biochim Biophys Acta
|Elustondo PA, Negoda A, Kane CL, Kane DA, Pavlov EV (2014) Spermine selectively inhibits high-conductance, but not low-conductance calcium-induced permeability transition pore. Biochim Biophys Acta 1847:231–40.|
Abstract: The permeability transition pore (PTP) is a large channel of the mitochondrial inner membrane, the opening of which is the central event in many types of stress-induced cell death. PTP opening is induced by elevated concentrations of mitochondrial calcium. It has been demonstrated that spermine and other polyamines can delay calcium-induced swelling of isolated mitochondria, suggesting their role as inhibitors of the mitochondrial PTP. Here we further investigated the mechanism by which spermine inhibits the calciuminduced, cyclosporine A (CSA) - sensitive PTP by using three indicators: 1) calcium release from the mitochondria detected with calcium green, 2) mitochondrial membrane depolarization using TMRM, and 3) mitochondrial swelling by measuring light absorbance. We found that despite calcium release and membrane depolarization, indicative of PTP activation, mitochondria underwent only partial swelling in the presence of spermine. This was in striking contrast to the high-amplitude swelling detected in control mitochondria and in mitochondria treated with the PTP inhibitor CSA. We conclude that spermine selectively prevents opening of the high-conductance state, while allowing activation of the lower conductance state of the PTP. We propose that the existence of lower conductance, stress-induced PTP might play an important physiological role, as it is expected to allow the release of toxic levels of calcium, while keeping important molecules (e.g., NAD) within the mitochondrial matrix.
• Keywords: Mitochondrial permeability transition pore, Spermine, Calcium green 5N
Labels: MiParea: Respiration
Stress:Permeability transition Organism: Rat Tissue;cell: Liver Preparation: Isolated mitochondria
Coupling state: LEAK Pathway: N HRR: Oxygraph-2k, O2k-Fluorometer
Calcium Green 5N, CaG